Carbon nanotubes (CNTs) have been considered in connection with permeable membranes for fluid separation for some time. Such membranes often rely on unusual transport properties of fluids through the nanotubes to improve performance. For example, enhanced transport through carbon nanotubes has been considered in U.S. Pat. No. 8,038,887.
However, it remains relatively difficult to fabricate permeable membranes having carbon nanotubes (CNTs) as the active material for separation. One significant reason for this is that active layers in permeable membranes are subject to numerous requirements (e.g., reliability, fouling resistance, high flux, good separation capability, etc.) and it can be difficult to meet these requirements with active layers that include carbon nanotubes. Another issue that can arise with such membranes is that CNTs may not provide sufficient separation capability. For example, small ions are difficult to filter out with CNTs.
Accordingly, it would be an advance in the art to provide high-performance separation membranes that are easier to fabricate.